The present invention relates to tying vises and more specifically to an improvement in the mechanism for holding a fishhook in the jaws of such a device.
Fly tying vises are not new per se. Typical of the prior art fly tying vises to which the present invention relates are those shown in the prior Renzetti U.S. patents listed below.
a) Renzetti U.S. Pat. No. 4,169,562
b) Renzetti U.S. Pat. No. 5,169,079
These vises typically comprise a base and an upstanding adjustable height beam extending up from the base, a rotary shaft mounted at the upper end of the height beam which has an offset portion mounting a jaw assembly for supporting a hook positioning the shank portion of the hook coaxial with the rotational axis of rotary shaft thereby permitting the creation of a precision fly.
In the Renzetti ""079 patent, the tips of the jaw assemblies are normally biased to an open position by spring means and can be adjusted to grip a fish hook by a rotatable cam element having continuously tapered planar surfaces which mate and confront complementary planar cam follower surfaces on the jaws opposite the tip ends to provide a surface to surface contact between the cam surfaces and the follower surfaces on the jaws. By this arrangement, the spread or distance between the tips of the jaws may be selectively adjusted between an open position spaced apart an adequate distance to permit insertion of a hook and a closed, locked position by rotating the cam to close the jaws to firmly grip the hook for the fly tying operation.
Even though the Renzetti ""079 patent shows a system which functions well for the purposes intended, the precision required to make the inter-engaging cam surfaces and the jaw follower surfaces are rather costly.
With the foregoing in mind, it is therefore an object of the present invention to provide a fly tying vise generally similar to that described in the Renzetti ""097 patent having an improved system for adjusting the distance between the tips of the jaws which is considerably more economical to make.
With this in mind, in accordance with the present invention, the inner end of each of the jaws is provided with a spherical projection which provides a line contact with the planar rotary cam surfaces. In accordance with another embodiment of the invention, the confronting faces of the terminal ends of the jaws are provided with pockets for spherical rolling elements which function as cam followers and engage the planar surfaces of the rotatable cam element. It has been found that this arrangement is much more economical to machine.